# CVE-2026-101090: Nezha Host header injection in OAuth2 redirect endpoint

Source: https://junglewise.ai/threats/cve-2026-101090-nezha-2-2-3-contains-a-host-header-injection-regression-in-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-27. Updated: 2026-09-27  
License: CC BY 4.0 with a link back

CVE-2026-101090 · Severity: critical · CVSS 9.8 · Published 2026-09-27

Nezha is a monitoring and remote management platform that supports OAuth2-based authentication. Version 2.2.3 contains a regression where the OAuth2 login endpoint reflects attacker-supplied Host headers into the redirect URL sent to identity providers, allowing attackers to intercept authorization codes and take over user accounts. This affects deployments where the optional dashboard_host setting is left empty.

Technologies: [github.com/nezhahq/nezha (Go)](https://junglewise.ai/threats/technologies/github-com-nezhahq-nezha), [Nezha](https://junglewise.ai/threats/technologies/nezha-nezha). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Nezha](https://junglewise.ai/threats/vendors/nezha).

## Quick answers

**Is CVE-2026-101090 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101090 being exploited in the wild.

**How severe is CVE-2026-101090?** Critical severity, with a CVSS score of 9.8, published 27 September 2026.

**Which products and versions are affected?** github.com/nezhahq/nezha (Go) SEMVER:introduced=0; Nezha 2.2.3.

**Is there a fix for CVE-2026-101090?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-101090 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-101090?** Check whether you run github.com/nezhahq/nezha (Go) or Nezha at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a Host header injection in /api/v1/oauth2/{provider} (oauth2.go) that occurs when dashboard_host is empty; the endpoint reflects the request Host header into the OAuth2 redirect_uri instead of falling back to install_host. An attacker with network access can forge the Host header on a request to Nezha, causing the OAuth2 provider to redirect the victim's authorization code to an attacker-controlled origin if that origin is accepted by the provider. The issue regresses a prior fix (GHSA-9rc6-8cjv-rcvx) and requires the specific configuration of empty dashboard_host with OAuth2 enabled.

## Affected products

- Nezha Nezha 2.2.3

## Identifiers

- CVE-2026-101090
- GO-2026-6486

## Timeline

- 2026-09-27: disclosed
- 2026-06-20: advisory: GitHub Security Advisory GHSA-rf68-8gjr-36q7 published

## References

- [https://github.com/nezhahq/nezha/security/advisories/GHSA-rf68-8gjr-36q7](https://github.com/nezhahq/nezha/security/advisories/GHSA-rf68-8gjr-36q7)
- [https://www.vulncheck.com/advisories/nezha-through-2.2.3-host-header-injection-via-oauth2-redirect-uri](https://www.vulncheck.com/advisories/nezha-through-2.2.3-host-header-injection-via-oauth2-redirect-uri)

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